COLORADO SPRINGS, Colo.  There isn't much stopping cheaters from using human growth hormone these days. In the minds of many experts, it has become the most insidious drug on the long list of banned substances in sports.

Ten years since HGH became a household item in the doping kits of dirty athletes, the problem seems little closer to being resolved.

Anti-doping leaders still are trying to find a test to efficiently detect it. Law enforcement is making inroads into distribution networks but is struggling to find ways to prosecute people for using HGH. And buoyed by the fact that it's hard to get caught, athletes also seem to be ignoring the drug's possible negative side effects.

"They just have to make sure they don't get caught with the drug in their bag," Peter Sonksen, a British professor who has studied HGH for four decades, said in a recent interview with the BBC.

Baseball, still reacting to Barry Bonds' indictment, is thought to be only weeks away from the release of the Mitchell report about the use of performance-enhancing drugs in its sport. But there's already an impressive list of players among those accused of receiving HGH - Paul Byrd, Gary Matthews Jr., Jason Grimsley, Bonds.

But baseball players aren't the only ones linked to HGH. Boxers, wrestlers, NFL players, coaches and doctors and bodybuilders are among those whose names have surfaced in a handful of ongoing steroid and HGH investigations.

Meanwhile, the Olympics are only 10 months away, and there's a growing perception that runners, swimmers and cyclists, among others, will use HGH in Beijing next year with very little chance of getting caught.

In fact, because of the cost of a test and the problems in mass producing one, there is no league or sports entity that currently regularly screens for HGH.

Arne Ljungvist, vice president of the World Anti-Doping Agency, said he wouldn't speculate when asked if a 100 percent effective HGH test will ever be found. "On the other hand, we have a recent thesis that shows that intake of HGH doesn't have that much effect," he said.

If they could only get the athletes to believe it.

Widely perceived as one of the most popular banned substances out there, HGH is thought to accentuate the effectiveness of other steroids.

One reason HGH is so hard to detect, even with the best blood tests, is because the pituitary gland puts it out in pulses - not as a constant stream - and it clears the system very quickly.

Produced in the anterior pituitary gland, growth hormone sends signals to other parts of the body, which release their own chemicals to stimulate growth. Cartilage produces one sort of chemical, bone another, internal organs another.

"If you took 10 people off the street at a random time and drew blood from them all, it's quite possible nine would have no detectable growth hormone in their blood," said Larry Bowers, the U.S. Anti-Doping Agency's head scientist.

That limits the effectiveness of the best test that currently exists to detect growth hormone.

In that test, the window of opportunity for detection is so small - 48 to 72 hours - that it makes the test basically unusable for in-competition purposes.

When a version of the test was used at the Athens and Turin Olympics, no positive results resulted, mainly because any athlete who was using the drug would have known to stop in time for any trace to clear his system.

Another test, versions of which have been developed by Sonksen and others, seeks the chemicals that stimulate growth once the HGH triggers their release. There is a much longer window of opportunity for that test - experts believe between seven and 17 days - but searching for these so-called "biomarkers" of HGH has its own complications that has limited the viability of that test in the eyes of many in the anti-doping establishment.

"Could we use both tests together? You bet," Bowers said. "I'd imagine some day, there would be some combination of the two that gives us the final answer."

But it will be expensive. Bowers estimated it costs about $40 to run an HGH test, and that's before adding the cost of drawing blood and other administrative functions. That may not sound like much, but consider a standard doping urine test, which costs $200, screens for about 150 banned compounds. An HGH test looks for one.

Although cycling, swimming, track and cross country skiing federations all allow blood testing, many other sports and their unions steadfastly have opposed having their players give blood.

"Think about a blood test," NFL union head Gene Upshaw said earlier this year. "There is no conclusive evidence it even works, that's the first thing. Second, to even detect HGH in your system, it almost has to be done when it's taken. That means our guys would have to be pin cushions. They're not going to be pin cushions."

Both baseball and the NFL have given Don Catlin, former head of the UCLA testing lab, money to do research on a urine test that might detect the substance. But less than .01 percent of growth hormone ends up in the urine at any one time, and that's not enough to detect its presence. At least not at this point in the science.

"If someone's looking for a quick fix, knowing what I know about growth hormone in blood, it's not there," Bowers said. "It's going to be 10 years until they have a urine test for growth hormone."

By then, it would also figure that some of the side effects of growth hormone might be better documented. Because it has only been produced synthetically for about 15 years, and used as a performance-enhancing drug for less than that, it's hard to see proof of the side effects yet.

The most common already known is called acromegaly, a disease better known as giantism. HGH spurs growth of cartilage often beyond what the bones can handle. It can lead to huge, gnarled hands and feet that could become susceptible to arthritis. Cartilage that connects the skull can also overgrow, leading to oversized heads.

HGH also stunts insulin production in the liver.

"I'm sort of waiting to hear about the first group of athletes who get diabetes because of growth hormone," Bowers said.

But USADA and other anti-doping agencies walk a fine line with this kind of drug, because it does have legitimate, therapeutic uses, mainly for children who don't grow to normal sizes and for adults with pituitary gland problems.

They don't want to overstate the dangers of a drug that is legally used. But neither do they want to completely ignore the possible side effects, especially in the ever-growing education campaign they've launched for young athletes.

Of course, one other front on which to fight is the legal arena, which is where the only successes in nabbing HGH users have come thus far.

In three highly publicized busts, federal agents have nabbed makers and distributors of HGH. They are looking for the sources more than the users, though Jack Robertson, lead investigator on Operation Raw Deal, made news last month when he said athletes "at every level" eventually would be caught up in the stings.

The law, however, is confusing when it comes to HGH.

Though Congress passed a law in 1990 forbidding improper distribution of synthetic HGH, prosecutors have been balked at going after doctors who use the drug as part of an anti-aging regimen.

Many doctors say their patients can use it to cure pituitary problems - presumably allowed under the law - even though the so-called "problem" could be loosely defined as the pituitary gland's natural tapering off of HGH production at middle age.

There are other instances in which HGH is prescribed for uses that some might view as legitimate, but others may not.

For instance, Byrd said he was prescribed HGH to medicate a "pituitary tumor." Rick Ankiel, also linked to the receipt of HGH, said any drugs he had taken were prescribed by physicians.

Even with possession nearly impossible to prove or prosecute, legal measures are the only factors curtailing HGH use on any level at this point.

A reliable test that's available in large quantities seems farther away.

"We've spent a large portion of our budget on scientific research," said Scott Burns, the deputy drug czar at the White House. "WADA has great scientists. They're in the game on this, pushing hard to come up with test that is effective and that will also send word out to athletes that we have a test."

It's just a matter of time, Burns said, until that test is ready. But asked precisely when that day will come - next month, next year in Beijing, or sometime after that - he demurred.

"If I knew the answer, I'd probably have another job instead of being some midlevel bureaucrat in the White House," he said. "But scientists I talk to say it's sooner rather than later."